At the start, you will only be able to activate hero power a maximum of twice per song (less if you miss). However, you can increase the amount of hero power sections in a song by upgrading your "hero sections" power. You start at level 1 and can upgrade all the way to level 4, which will take 30,000 coins. You'll need to do this anyway to get the "Specialist Shredder" and "Power Crazy!" achievements. Each upgrade gives you an additional hero power section, and the final upgrade unlocks all of the hero power sections in a song, which can be more than 10 in longer songs. If you fully upgrade this power you should unlock this achievement much quicker.